The Study On Sewage Reinjection Treatment Technology And Process In Qingshen Gas Field

Two methods are taken by gas production to deal with production sewage.First,the sewage is transported by tanker truck to the nearest oilfield station and treated after mixing with oilfield sewage.Second is that the gas gathering stations with relatively little outflow of water are directly discharged to the environment.There are many drawbacks to the treatment,which mainly manifests in: heavy workload,high cost,water quality can not meet the requirements of the platoon,pollute the environment and can not meet the environmental protection requirements.At the same time,as the scale of gas field development continues to increase,the amount of sewage produced in gas fields increases year by year,the two treatment methods will be difficult to adapt to the needs of sewage treatment in gas fields.Therefore,it is urgent to carry out research on the comprehensive treatment technology for the production of sewage from gas fields.This paper analyzes the characteristics of produced water in Qingshen Gas Field.The effects of gas field sewage on reservoir damage are studied through core experiments,core water sensitivity assessment,static compatibility test of sewage,and dynamic compatibility experiment and the damage of injected water to the reservoir is evaluated.Meanwhile,combined with re-injection of sewage quality indicators of the field test of Sheng 65 well,the results show that the sewage from the gas field must be treated to a certain extent before the invalid reinjection.The injecting capacity of sewage at Shengshen 2 gas gathering station is evaluated.The results show that when the raw water is treated until the oil content less than 10 mg/L,the suspended matter content of 6.5mg/L,and the median particle size was about 3.6?m.The pressure rises more slowly,and the reservoir permeability drops by about 30% during the injection process.On this basis,the invalid reinjection capacity will be further improved by finely filtering the water quality or adopting a combination of physical and chemical methods for deep processing.Therefore,when the main water quality control index meet oil content Co <10mg/L,suspended solids Cs ?6mg/L,particle size median ??3?m,the invalid reinjection can be carried out.And under the guidance of the preferred principles of sewage treatment process and the principle of optimization,the sewage treatment process is proposed and the invalid injection capacity of the sewage from the gas field is predicted.